Tolmachov Oleg E
Section of Molecular Medicine, National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Med Hypotheses. 2014 Aug;83(2):211-6. doi: 10.1016/j.mehy.2014.04.027. Epub 2014 May 2.
Tightly controlled spatial localisation of therapeutic gene delivery is essential to maximize the benefits of somatic gene therapy in vivo and to reduce its undesired effects on the 'bystander' cell populations, most importantly germline cells. Indeed, complete ethical assurance of somatic gene therapy can only be achieved with ultra-targeted gene delivery, which excludes the risk of inadvertent germline gene transfer. Thus, it is desired to supplement existing strategies of physical focusing and biological (cell-specific) targeting of gene delivery with an additional principle for the rigid control over spread of gene transfer within the body. In this paper I advance the concept of 'combinatorial' targeting of therapeutic gene transfer in vivo. I hypothesize that it is possible to engineer complex gene delivery vector systems consisting of several components, each one of them capable of independent spread within the human body but incapable of independent facilitation of gene transfer. As the gene delivery augmented by such split vector systems would be reliant on the simultaneous availability of all the vector system components at a predetermined body site, it is envisaged that higher order reaction kinetics required for the assembly of the functional gene transfer configuration would sharpen spatial localisation of gene transfer via curtailing the blurring effect of the vector spread within the body. A particular implementation of such split vector system could be obtained through supplementing a viral therapeutic gene vector with a separate auxiliary vector carrying a non-integrative and non-replicative form of a gene (e.g., mRNA) coding for a cellular receptor of the therapeutic vector component. Gene-transfer-enabling components of the vector system, which would be delivered separately from the vector component loaded with the therapeutic gene cargo, could also be cell-membrane-insertion-proficient receptors, elements of artificial transmembrane channels capable of nucleic acid transfer or, perhaps, factors modifying existing cellular transmembrane channels (e.g., gap-junctional hemichannels) to serve as conduits for gene entry. In general, there are four possibilities for gene transfer in vivo using a split vector system: (1) simultaneous delivery of a mixture of the vector components to the same body site; (2) sequential delivery of the vector components to the same body site; (3) simultaneous delivery of the vector components to separate body sites; (4) sequential delivery of the vector components to separate body sites. It is hoped that, once experimentally confirmed, the combinatorial principle for tight control over localisation of gene transfer could be the critical element in attaining complete assurance of gene non-delivery to germline cells in somatic gene therapy in vivo.
严格控制治疗性基因递送的空间定位对于在体内最大化体细胞基因治疗的益处以及减少其对“旁观者”细胞群体（最重要的是生殖细胞）的不良影响至关重要。事实上，只有通过超靶向基因递送才能实现体细胞基因治疗的完全伦理保证，这排除了无意的生殖系基因转移风险。因此，期望用一种额外的原则来补充现有的基因递送物理聚焦和生物（细胞特异性）靶向策略，以严格控制基因转移在体内的扩散。在本文中，我提出了体内治疗性基因转移“组合”靶向的概念。我假设可以设计由几个组件组成的复杂基因递送载体系统，其中每个组件都能够在人体内独立扩散，但不能独立促进基因转移。由于这种分裂载体系统增强的基因递送将依赖于所有载体系统组件在预定身体部位同时可用，因此可以设想，功能性基因转移配置组装所需的高阶反应动力学将通过减少载体在体内扩散的模糊效应来锐化基因转移的空间定位。这种分裂载体系统的一种特定实现方式可以通过用携带编码治疗性载体组件细胞受体的基因（例如mRNA）的非整合和非复制形式的单独辅助载体补充病毒治疗性基因载体来获得。载体系统的基因转移启用组件，将与装载治疗性基因货物的载体组件分开递送，也可以是细胞膜插入熟练的受体、能够进行核酸转移的人工跨膜通道元件，或者也许是修饰现有细胞跨膜通道（例如间隙连接半通道）以作为基因进入管道的因子。一般来说，使用分裂载体系统在体内进行基因转移有四种可能性：（1）将载体组件的混合物同时递送至同一身体部位；（2）将载体组件顺序递送至同一身体部位；（3）将载体组件同时递送至不同身体部位；（4）将载体组件顺序递送至不同身体部位。希望一旦通过实验得到证实，严格控制基因转移定位的组合原则可能是在体内体细胞基因治疗中完全保证基因不递送至生殖细胞的关键要素。
